This is a note to let you know that I've just added the patch titled
x86/vsyscall/64: Explicitly set _PAGE_USER in the pagetable hierarchy
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: x86-vsyscall-64-explicitly-set-_page_user-in-the-pagetable-hierarchy.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 49275fef986abfb8b476e4708aaecc07e7d3e087 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski luto@kernel.org Date: Sun, 10 Dec 2017 22:47:19 -0800 Subject: x86/vsyscall/64: Explicitly set _PAGE_USER in the pagetable hierarchy
From: Andy Lutomirski luto@kernel.org
commit 49275fef986abfb8b476e4708aaecc07e7d3e087 upstream.
The kernel is very erratic as to which pagetables have _PAGE_USER set. The vsyscall page gets lucky: it seems that all of the relevant pagetables are among the apparently arbitrary ones that set _PAGE_USER. Rather than relying on chance, just explicitly set _PAGE_USER.
This will let us clean up pagetable setup to stop setting _PAGE_USER. The added code can also be reused by pagetable isolation to manage the _PAGE_USER bit in the usermode tables.
[ tglx: Folded paravirt fix from Juergen Gross ]
Signed-off-by: Andy Lutomirski luto@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: David Laight David.Laight@aculab.com Cc: H. Peter Anvin hpa@zytor.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Juergen Gross jgross@suse.com Cc: Kees Cook keescook@chromium.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/entry/vsyscall/vsyscall_64.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -37,6 +37,7 @@ #include <asm/unistd.h> #include <asm/fixmap.h> #include <asm/traps.h> +#include <asm/paravirt.h>
#define CREATE_TRACE_POINTS #include "vsyscall_trace.h" @@ -329,16 +330,47 @@ int in_gate_area_no_mm(unsigned long add return vsyscall_mode != NONE && (addr & PAGE_MASK) == VSYSCALL_ADDR; }
+/* + * The VSYSCALL page is the only user-accessible page in the kernel address + * range. Normally, the kernel page tables can have _PAGE_USER clear, but + * the tables covering VSYSCALL_ADDR need _PAGE_USER set if vsyscalls + * are enabled. + * + * Some day we may create a "minimal" vsyscall mode in which we emulate + * vsyscalls but leave the page not present. If so, we skip calling + * this. + */ +static void __init set_vsyscall_pgtable_user_bits(void) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + pgd = pgd_offset_k(VSYSCALL_ADDR); + set_pgd(pgd, __pgd(pgd_val(*pgd) | _PAGE_USER)); + p4d = p4d_offset(pgd, VSYSCALL_ADDR); +#if CONFIG_PGTABLE_LEVELS >= 5 + p4d->p4d |= _PAGE_USER; +#endif + pud = pud_offset(p4d, VSYSCALL_ADDR); + set_pud(pud, __pud(pud_val(*pud) | _PAGE_USER)); + pmd = pmd_offset(pud, VSYSCALL_ADDR); + set_pmd(pmd, __pmd(pmd_val(*pmd) | _PAGE_USER)); +} + void __init map_vsyscall(void) { extern char __vsyscall_page; unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);
- if (vsyscall_mode != NONE) + if (vsyscall_mode != NONE) { __set_fixmap(VSYSCALL_PAGE, physaddr_vsyscall, vsyscall_mode == NATIVE ? PAGE_KERNEL_VSYSCALL : PAGE_KERNEL_VVAR); + set_vsyscall_pgtable_user_bits(); + }
BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_PAGE) != (unsigned long)VSYSCALL_ADDR);
Patches currently in stable-queue which might be from luto@kernel.org are
queue-4.14/x86-entry-rename-sysenter_stack-to-cpu_entry_area_entry_stack.patch queue-4.14/x86-mm-put-mmu-to-hardware-asid-translation-in-one-place.patch queue-4.14/x86-vsyscall-64-explicitly-set-_page_user-in-the-pagetable-hierarchy.patch queue-4.14/x86-uv-use-the-right-tlb-flush-api.patch queue-4.14/x86-mm-dump_pagetables-check-page_present-for-real.patch queue-4.14/x86-ldt-prevent-ldt-inheritance-on-exec.patch queue-4.14/x86-microcode-dont-abuse-the-tlb-flush-interface.patch queue-4.14/x86-doc-remove-obvious-weirdnesses-from-the-x86-mm-layout-documentation.patch queue-4.14/init-invoke-init_espfix_bsp-from-mm_init.patch queue-4.14/x86-cpu_entry_area-move-it-to-a-separate-unit.patch queue-4.14/x86-vsyscall-64-warn-and-fail-vsyscall-emulation-in-native-mode.patch queue-4.14/x86-mm-create-asm-invpcid.h.patch queue-4.14/x86-mm-remove-superfluous-barriers.patch queue-4.14/x86-ldt-rework-locking.patch queue-4.14/arch-mm-allow-arch_dup_mmap-to-fail.patch queue-4.14/x86-cpu_entry_area-move-it-out-of-the-fixmap.patch queue-4.14/x86-mm-remove-hard-coded-asid-limit-checks.patch queue-4.14/x86-kconfig-limit-nr_cpus-on-32-bit-to-a-sane-amount.patch queue-4.14/x86-mm-add-comments-to-clarify-which-tlb-flush-functions-are-supposed-to-flush-what.patch queue-4.14/x86-mm-move-the-cr3-construction-functions-to-tlbflush.h.patch queue-4.14/x86-mm-dump_pagetables-make-the-address-hints-correct-and-readable.patch queue-4.14/x86-insn-eval-add-utility-functions-to-get-segment-selector.patch queue-4.14/x86-mm-use-__flush_tlb_one-for-kernel-memory.patch queue-4.14/x86-mm-64-improve-the-memory-map-documentation.patch